(a) Field of the Invention
The present invention relates to a shift rod support assembly for a transmission gear shift mechanism, and more particularly, to a shift rod support assembly for a transmission gear shift mechanism in which the adjustment of play between a shift rod and support assembly is easy and resistance during a selecting operation of a shift lever is reduced, thereby resulting in the reduction of noise during operation, and improvement in the overall durability and smooth operation of the transmission gear shift mechanism.
(b) Description of the Related Art
There are a variety of types of transmission gear shift mechanisms for controlling a manual transmission, depending on transmission type and the location of the transmission. The two main categories of transmission gear shift mechanisms are the direct-operation type and the remote-operation type. In the remote-operation type transmission gear shift mechanism, the shift lever and transmission are separated by a substantial distance, and a shift rod or cable connects these two elements to permit interaction therebetween. The shift rod or cable transmits the force applied to the shift lever by the driver to the transmission, which, in the case where the remote-operation type transmission gear shift mechanism is applied, is mounted toward the rear of the vehicle. When the shift rod is used, a support assembly for supporting the shift rod is provided at a suitable location.
A guide-type support assembly is an example of such a shift rod support assembly. The guide-type support assembly includes a plastic bracket mounted at a suitable location of the transmission gear shift rod and to a vehicle body. Also, a cylindrical rubber boot, which prevents the entrance of foreign substances, is provided around an external surface of the bracket along a longitudinal direction of the shift rod. An advantage of the bracket is its low price, but the bracket has a limited durability and is particularly susceptible to wear by rectilinear and rotational motion of the shift rod.
Since it is not possible to minimize such wear, the development of play between the shift rod and support assembly is unavoidable. This results in the generation of noise when driving on an uneven road surface. That is, the motion of the shift rod within the support assembly as a result of the play between these two elements causes the generation of a raffling noise particularly when driving on an uneven road surface. Therefore, roller-type support assemblies are now more commonly used than guide-type support assemblies.
FIG. 1 shows a perspective view of a roller-type support assembly for a transmission gear shift rod.
As shown in the drawing, brackets 112 and 114 are provided at a predetermined location and on opposite sides of a circumference of a shift rod 110. An upper roller 116 and a lower roller 118 are mounted between the brackets 112 and 114 on opposite sides of the shift rod 110 and in contact with the shift rod 110 such that the upper and lower rollers 116 and 118 are substantially perpendicular to a plane made by the brackets 112 and 114. Rubber boots 120 and 122 are mounted around the circumference of the shift rod 110 at predetermined positions. The rubber boots 120 and 122 are cylindrical and in close contact with the shift rod 110. In operation, the upper and lower rollers 116 and 118 rotate during rectilinear motion of the shift rod 110 as shown by the arrows in the drawing. The lower roller 118 is particularly concave where contact is made with the shift rod 110 to enable rotation.
Although the roller-type support assembly produces less noise and is more durable than the guide-type support assembly, because the rollers 116 and 118 rotate only during rectilinear motion of the shift rod 110), rotational motion of the shift rod 110) is not effectively performed (the shift rod 110 typically undergoes rectilinear motion to effect shifting into different gears and rotational motion to effect shifting into different shift ranges). Therefore, more force is needed in manipulating the shift lever when selecting a shift range.
Further, the rollers 116 and 118 wear over time by the rectilinear and rotational motion of the shift rod 110 such that a gap develops between the rollers 116 and 118 and the shift rod 110. This gap causes play between the shift rod 110 and the support assembly, and since it is not possible to remove the developing gap, it is not possible to compensate for the play between these elements.
The present invention has been made in an effort to solve the above problems.
It is an object of the present invention to provide a shift rod support assembly for a transmission gear shift mechanism, in which the adjustment of play between a shift rod and support assembly is easy and resistance during a rotational operation of a shift lever is reduced, thereby resulting in the reduction of noise during operation and improvement in the overall durability and smooth operation of the transmission gear shift mechanism.
To achieve the above object, the present invention provides a shift rod support assembly for a transmission gear shift mechanism comprising a housing fixed to a vehicle body and including a hole through which the shift rod passes; a ball case including a fixed unit that is fixedly mounted to the housing and has a hole through which the shift rod passes, and a protrusion portion extending toward an inner area of the housing from the fixed unit and having a plurality of ball insertion holes; a plurality of balls, each provided in one of the ball insertion holes in a state whereby they contact the shift rod, the balls rotating as the shift rod undergoes rectilinear and rotational motion; rollers provided in a space formed by the housing and the ball case, the rollers contacting and rotating together with the balls; and play adjustment members for adjusting play between the rollers and the balls by manipulating a positioning of the rollers relative to the housing and the ball case.
According to a feature of the present invention, the play adjustment members comprise inner columns provided within the rollers and about which the rollers are able to rotate; and fixed rods fixedly provided off-center within the inner columns, ends of the fixed rods being fixed to the housing and the ball case.
According to another feature of the present invention, lubrication holes are provided in the inner columns to enable contact surfaces between the inner columns and the rollers to be lubricated.
According to yet another feature of the present invention, at least one of the ends of the fixed rods is threaded such that a nut may be screw-coupled onto the threads, and a center portion of the fixed rods between the ends is rectangular and fits into a corresponding hole provided in the inner columns such that when at least one of the ends of the fixed rods is secured, the inner columns also remain fixed.
According to still yet another feature of the present invention, the housing and the ball case are made of a material such as Teflon or polyethylene, which have exceptional durability and undergo no alteration as a result of contact with grease.
According to still yet another feature of the present invention, grooves are formed on a surface of the balls to minimize a contact surface between the balls and the rollers.
According to still yet another feature of the present invention, the ball case is screw-coupled onto the housing.
According to still yet another feature of the present invention, the balls first contact the shift rod insertion holes before making contact with the shift rod.
According to still yet another feature of the present invention, an insertion portion is formed in an inner face of the housing and an end of the protrusion portion is inserted into the insertion portion.